Neuroendocrine and Immune Responses in Humans During and After Long Term Stay at ISS (Immuno) - 09.17.14

Science Objectives for EveryoneNeuroendocrine and Immune Responses in Humans During and After Long Term Stay at ISS (Immuno) provides an understanding for the development of pharmacological tools to counter unwanted immunological side-effects during long-duration missions in space.

Science Results for Everyone

This investigation analyzed the immune system of 30 astronauts on short- and long-duration missions. Observations include: no notable changes in antiviral antibody levels, specific antibodies for Epstein-Barr viruses. There is a marked increase in white blood cells, however no change in overall population of T- and B-lymphocytes. Observed decreases in T-lymphocyte function, cytokines (cell-signaling agents), and in population and activity of natural killer cells (defenders against microbes and toxins) could mean more susceptibility to potential infections. Because such alterations could compromise the body's defenses against pathogens, indepth studies of the post-flight immune system in human space explorers are essential.

The following content was provided by Alexander Chouker, M.D., and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Erasmus Experiment Archive.

The aim of this experiment is to determine changes in stress and immune responses, during and after a stay on the ISS. This will include the sampling of saliva, blood and urine to check for hormones associated with stress response and for carrying out white blood cell analysis. There will also be a focus on the adaptation of energy metabolism, which can affect immune response.

An increased understanding of the coupling between stress and the functioning of the immune system also has relevance for people on Earth.

Description
Immuno will determine neuroendocrine and immunological changes during and after working and living on the ISS. A focus on cellular energy metabolism and cell signaling will provide additional information on the psycho-neuroendocrine and immunologic adaptation of human physiology to space and a better insight on how these processes are dependent on the cellular level of signal processing.

Operational Requirements
Immuno will involve taking several preflight and inflight measurements. A Current Stress Test (CST), paper stress test designed to repeatedly determine an individuals' psychological state under the conditions of acute and chronic stress, is taken. A urine collection will be performed for determination of dopamine or epinephrine in urine collected within 24 hours. A saliva collection will be performed in the morning and in the evening by chewing on a cotton swab for 30-45 seconds. Fluid will then be removed from the swab by centrifugation and kept frozen at -20 degrees C. Blood collections will also be performed to analyze the blood and blood components. This experiment is planned to be carried out over multiple ISS Increment crews, requiring six subjects in total.

Operational Protocols
A preflight test will be conducted between launch minus 30 days (L-30) and launch minus 7 days (L-7). Two inflight sample collections will occur; the first between launch plus 30 days (L+30) and launch plus 90 days (L+90). The second inflight sample collection will occur between launch plus 150 days (L+150) and return minus 14 days (R-14).

Thirty (30) cosmonauts on short-duration (8–11 days) and long-duration (125–195 days) missions to ISS were studied before launch and after landing in order to detect changes in the immune system which had been reported in previous studies with short- and long-duration space missions in low Earth orbit (LEO).

In 2008, Rykova et al. published the first results on the Humoral Immune Response (HIR) of ISS cosmonauts. The HIR study focused on peripheral blood antibodies, T- and B-lymphocyte white blood cell (WBC) populations, cytokines (cell-signaling agents), as well as natural killer (NK) cells activity in the body’s defense against bacteria, viruses, and toxins.

No notable changes in the antiviral antibody levels after long- and short-term missions were observed, and specific antibodies for Epstein-Barr viruses (EBVs), which were often reactivated in microgravity, also did not change. Although the total number of WBCs increased significantly upon landing, the overall population of T and B lymphocytes did not change appreciably after long-duration space flights. However, T-lymphocyte function was decreased which supports previous observations and recently confirmed by Morukov et al. from a study of 12 Russian cosmonauts after long-duration missions. Researchers proposed that a long-duration space flight, perhaps coupled with several extravehicular activities (EVA), activated and suppressed T-lymphocytes’ response to proliferate, thus resulted in an immune deficit against potential infections. The investigation also showed gross individual differences in concentration of cytokines before launch due possibly to preflight stress. The random changes after short- and long-term missions suggest that cytokines may be highly sensitivity to the factors associated with reentry and readaptation to Earth’s gravity. Also, a decrease in natural killer (NK) cells population and activity in the long-duration crewmembers may be an indication of a weakened immune system, plus the reduced NK activity in some subjects on the first day after short-duration could very well be an acute response to landing stress.

Many improvements have been made to the living conditions of orbital vehicles and the scope of space flight immunological research expanded since the first human was flown into space 50 years ago. However, ISS crewmembers still exhibit negative shifts in the immune system during initial readaptation to gravity. Such alterations, scientists suspect, could lead to compromised defenses against infections by limiting the immune system’s communicating and disease fighting capabilities. In light of these results, full characterization of all aspects of the innate and adaptive immune system after prolonged and brief flights appears essential for understanding the relationship of microgravity and stress effects of space flight on human space explorers (Rykova et al. 2008, Morukov et al. 2011).